Perhaps you should try some spelling variations:
khoan khau » khoanh khac, khoa kham, khoa phau
than thong » than thuong, toan thong, tran thong
khau thong » khau thuong, khap thong, khau tong
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
khoa than » khoa luan, hoa thai, hoa tan
mai thach » mai thanh, tai thanh, oai thanh
thach cac » thac cac, thanh cac, tich cac
thuc cac » thuc cach, tuc cac, phuc cac
cac khoa » cac khoi, dac khoa, cao khoa
te sach » toc sach
tu bach » vu bach, tu cach, tu bac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach tren thuc cac khoa than thong ) or ( tu bach mai thach cac khoan khau thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach tren thuc cac khoa than thong ) OR ( tu bach mai thach cac khoan khau thong )).
• Adding a wildcard symbol may retrieve word variants: (( te sach tren thuc cac khoa than thong ) or ( tu bach mai thach cac khoan khau thong ))*.